feat(admin): plan statistics + node restart/close-ae actions

Final legacy-admin items:
- identity GET /v1/admin/plan-statistics (active/total users + revenue per plan
  from user_plans); surfaced as a breakdown table in /admin/stats
- NodesTable: wire Restart + Close-AE actions (backend already supported them) via
  new proxy routes; was only drain/release before

Full DivineGateWeb legacy-admin parity achieved.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/app/api/admin/nodes/[nodeId]/close-ae/route.ts

@@ -0,0 +1,9 @@
+import { type NextRequest } from "next/server";
+import { adminProxy } from "@/app/api/admin/_adminProxy";
+
+export const runtime = "nodejs";
+interface Ctx { params: { nodeId: string } }
+
+export async function POST(req: NextRequest, { params }: Ctx) {
+  return adminProxy(req, `/v1/nodes/${params.nodeId}/close-ae`);
+}

src/app/api/admin/nodes/[nodeId]/restart/route.ts

@@ -0,0 +1,9 @@
+import { type NextRequest } from "next/server";
+import { adminProxy } from "@/app/api/admin/_adminProxy";
+
+export const runtime = "nodejs";
+interface Ctx { params: { nodeId: string } }
+
+export async function POST(req: NextRequest, { params }: Ctx) {
+  return adminProxy(req, `/v1/nodes/${params.nodeId}/restart`);
+}